Oil burning installations for furnaces



Jan. 15, 1963 E. D. HoBsoN 3,073,376

OIL BURNING INSTALLATIONS FOR FURNACES Filed Feb. 4, 1958 2 Sheets-Sheet 1 E. D. HOBSON OIL BURNING INSTALLATIONS FOR FURNACES Jan. 15, 1963 2 Sheets-Sheet 2 Filed Feb. 4, 1958 arent lfiettenterl dan. 15, 1963 Fie This invention relates to oil burning installations for furnaces and to improved means for operating such in y stallations.

An oil burning installation using spill type burners has previously been proposed including a low pressure pump for delivering cold viscous oil to a heater, the oil discharged from the heater being delivered to the burners by a high pressure pump. According to this prior proposal oil spilled over at the burners was taken olfV through a bypass conduit and delivered into a mixing chamber located in the oil ow line between the heater and the low pressure pump so as to be mixed with the cold oil delivered by the latter pump.

According to the present invention an oil burning installation for a furnace comprises a pump connected in the oil tlow line for delivering oil to oil heating means, a second pump operating at a higher pressure than the lirst for delivering oil from the heater to the oil burners of the furnace, means for controlling the oil supply to the burners comprising a valve controlled by-pass connected with the oil flow line between the burner inlet and the high pressure pump and means for returning the oil owing through said by-pass into the oil llow line at a point between the heating means and the first mentioned pump.

To enable the invention to be fully understood it will now be described with reference to the accompanying drawings, in which:

FIG. l illustrates in diagrammatic form an oil burning installation according to one embodiment of the invention.

FIG. 2 is a fragmentary view illustrating one form of control for the oil heater, and

FIG. 3 is a view illustrating an alternative form of control.

As shown in FIG. l of the accompanying drawings, an oil burning installation includes a low pressure pump 1 having its inlet connected to a pipe 2 connected to a storage tank (not shown) containing oil which will normally be at a relatively low temperature. As shown a strainer 3 is provided in the pipe 2. The discharge side ofthe pump 1 is connected with a pipe 4 leading to a mixing chamber 5 whose discharge side is connected to a pipe leading to the infeeds of a pair of heat exchangers 6, Each heat exchanger includes oil passages 7, 7a and steam passages 8, 8a, the steam passages having inlets 9 and an outlet 10. As shown in FIGURE 1, the mixing chamber 5 is an enlarged circular cylinder with its axis mounted in a vertical plane. The cold oil inlet pipe 4 conneclts to the center of the bottom of the cylinder.

The oil discharged from the heat exchangers Hows through a pipe 12 and filter `12a to a pump 13 which is adapted to operate at a higher pressure than the pump 1 and deliver the heated oil through the pipe 14 to the burners 1S of the furnace. As shown the burners are of the non-spill or simplex type and their inlets are connected by short feed'conduits 16 which are connected in parallel with the oil ilow line 14. A control or shut down valve 14a is arranged in each feed conduit so that when the installation is required to operate at low output one or more of the burners may be shut down.

A by-pass pipe 17 is connected between the supply pipe 14 and the mixing chamber 5. As shown the by-pass pipe 17 is connected in series with the burner supply pipe 14 adjacent to an downstream of the inlet ends of the burner feed conduits 16.

A regulator valve 18 is provided in the by-pass 17 and as the pump 13, and also the pump 1, is designed to run at constant speed, the valve 18 serves, by controlling the amount of oil diverted into the by-pass 17, to control the operation of the burners over a wide range.

Oil diverted through the by-pass 17 Hows into the mixing chamber 5 where it mixes with the relatively cold oil from the pump 1 and ows to the infeed of the heat exchangers d. v

The oil from the by-pass 17 is delivered into the mixing chamber S adjcent to its lower or inlet end, through nozzles 19 adapted to inject the oil in streams tangentially to the tlow path of the cold oil delivered by the pump 1.

lt -is desirable to maintain a substantially constant pressure, adequate to prevent vaporisation of the oil, at.

the inlet side of the high pressure pump 13 and to ensure this a by-pass pipe 2t) is connected between the discharge and inlet sides of the low-pressure pump 1, a pressure responsive valve '21 being provided, which is arranged to open automatically if the pressure at the suction side of the high pressure pump 13 exceeds a predetermined ligure, for example l0 lbs. above atmospheric pressure. As shown the valve 21 has a diaphragm disposed in a diaphragm chamber 22, one side of the diaphragm being connected by a pipe 23, to the suction side of the pump 13 and the other being connected to atmospher by a pipe 23a so that when the pressure at the suction side of the pump 13 exceeds the predeterminedlgure, for example l0 lbs. above atmospheric pressure thediaphragm will be actuated to open the valve 21.

It will be noted that the pipe 23 is connected in the tlow line to pump 13 downstream of the lter 12a and accordingingly the pressure at the suction side of the pump 13 can be accurately controlled and will not be aifected by the condition, for example choking up, of the filter.

To prevent damage to the high pressure pump in the event that for some reason the burner valves are not open when the installation is operating, a by-pass Z4, including a pressure relief valve 25, is provided between the discharge and inlet sides of the high pressure pump 13. This valve is, however, only a safety device and under normal conditions it will remain closed. A bypass 31 having a relief valve 32 is also provided connecting the inlet and outlet sides of the low pressure pump 1.

The pumps 1 and 13 are designed to run at constant speeds and as shown' are driven through suitable gearing by a common prime mover 26 such as a steam turbine. lf desired, however, each pump may be independently driven.

When the burners are required to operate at light load, instead of all the burners remaining in operation, any desired number can be completely shut down by the valves 14a, and for example only two burners left in usej ln this case the supply of oil would be curtailed by running the pumps 1, 13 at reduced speed, no adjustment of the heaters being required. When both pumps are driven by a common prime mover, the control of the latter would automatically effect a simultaneous and equal reduction in the speed of both pumps.

The temeprature of the heat exchangers d is adapted to be adjusted to ensure that the oil will be at a temperature such as to ensure elicient atomisation when it reaches the burners.

One form of temperature control is illustrated in FIG. 2, where as shown, the steam inlets 9 of the heat exchangers 6 are connected tol a common steam supply line 91a which has a valve A which is connected with a heat re sponsive element or device B located in the flow line 12 leading from the discharge side of the heat exchangers.

' to the burners.

lf desired either of the heat exchangers 6 may be shut down by closing the respective oil inlet and discharge valves 6a, 6b and the appropriate steam inlet valve 9b. It will be noted that the arrangement of the temperature control is such that the valve A will operate to control the ilow of heating steam irrespective as to Whether one or both heat exchangers are in use.

By this means when the burner is operating under light load and a relatively large quantity of oil is being bypassed and mixed with the incoming cold oil, the supply of heating steam to the heat exchangers can be greatly reduced Without impairing the ethciency of the installation.

An important advantage of the invention is that the heat used in raising the temperature of the proportion of the oil diverted into the 'oy-pass 17 is not wasted as it is recirculated into the system and serves to raise the ternperature of the cold oil delivered to the mixing chamber by the low pressure pump 1. Further the ow of oil through the heaters can be maintained at a substantially constant rate irrespective of the output of the burners so that even when the latter are operating at low output there will be a reasonably high rate of flow through the heater and in consequence the risk of overheating of the oil and coking within the heater, which would result if the tlow through the heater were very small, are avoidedA Another advantage is that the pressure at the output of the high pressure pump 13 will never need to exceed that actually required at the burners and accordingly an economy in input power for operating the pump is obtained.

A further advantage is that, by adjustment of the setting of the oil temperature control according to the grade of oil being consumed, the viscosity and pressure of the oil supplied to the high pressure pump 13 will remain unaltered regardless of its viscosity in the storage tank. In consequence the pressure characteristic at the output of this pump will be unaiected by the grade and temperature of the oil entering the low pressure pump 1, whether it be the normally used heavy boiler oil or any lighter and less viscous oil.

An important advantage of positioning the heater between the low and high pressure pump is that the heater may be designed to operate at the low pressure of the oil being supplied by the low pressure pump. An advantage of positioning the filter 12a between the pumps l, 13 is that the pressure in the iilter cannot exceed that of the pump 1, as the relief valve 32 will automatically open if the back pressure due to the iilter becomes excessive.

By maintaining constant viscosity and pressure of the fuel at the inlet of the high pressure pump 13 and selecting suitable pressure-output characteristics at the outlet side of this pump, correct burner inlet pressure is assured for any desired burner output by adjustment of the single regulator valve 18 which controls the rate at which oil flows through the by-pass 17. The provision of additional valves to control the flow of oil to the burners is accordingly obviated.

The regulator valve i8 may be operated by remote control from an instrument panel.

It will be understood that any desired number of burners may be included in the installation each burner being connected to the oil llow line leading from the high pressure pump.

The pumps 1 and 13 may 'ne of any convenient type and Cil 4 the heat exchanger may take other forms than that shown.

The installation may be made adaptable for various grades of fuel oil and to this end one or more valve controlled connections such as 28 may be provided for the lllow line on the suction side of the pump 1. For example a diesel oil supply pipe may be connected to the connection 2S and the supply to the pipe 2 shut off by closing the valve 29 and the diesel supply opened by opening the valve 3G.

The invention is particularly adapted for oil burning furnace installations for marine propulsion plant.

l claim:

l. An oil burning installation for a furnace comprising a. plurality of non-spill type pressure atoniizing burners, an oil iiow line connected with the supply side of the burners, a heater in said ow line, a mixing chamber connected in said ow line upstream of said heater, a low pressure pump for delivering oil fuel through said chamber to the heater, means for running said low pressure pump at constant speed, a plurality of burner feed conduit means each connecting the oil ow line to a burner, a by-pass conduit having one end connected with said oil how line at a point adjacent to and on the downstream side of said burner feed conduit means, the other end of said by-pass opening into said mixing chamber, a high pressure pump connected in the ilow line between the heater and the supply side of the burners for delivering the heated oil to the burners, means for running said high speed pump at constant speed, said mixing chamber comprising a cylindrical member, an axially disposed inlet port in the bottom thereof communicating with said low pressure pump for supplying oil at a relativ'ely low temperature, means maintaining the pressure at the inlet of the high pressure pump substantially constant comprising a second by-pass conduit connecting the discharge of said low-pressure pump to the inlet of said low-pressure pump, a valve in said second by-pass conduit, and means responsive to changes in pressure in the intake of said high-pressure pump to regulate said valve, and a single valve in said by-pass conduit for regulating the amount of oil by-passed from said ow line into the said mixing chamber.

2. An oil burning installation for a furnace comprising a plurality of non-spill type pressure atomizing burners, an oil flow line connected with the supply side of the burners, a heater in said ow line, a mixing chamber connected in said iiow line upstream of said heater, a low pressure pump for delivering oil fuel through said chamber to the heater, means for running said low pressure pump at constant speed, a plurality of burner feed conduit means each connecting the oil ow line to a burner, a by-pass conduit having one end connected with said oil flow line at a point adjacent to and on the downstream side of said burner feed conduit means, the other end of said by-pass opening into said mixing chamber, a high pressure pump connected in the ow line between the heater and the supply side of the burners for delivering the heated oil to the burners, means for running said high pressure pump at constant speed, said mixing chamber comprising a cylindrical member, an axially disposed inlet port in the bottom thereof communicating with said low pressure pump for supplying oil at a relatively low temperature, means maintaining the pressure at the inlet of the high pressure pump substantially constant comprising a second by-pass conduit connecting the discharge of said low-pressure pump to the inlet of said low-pressure pump, a valve in said second by-pass conduit, and means responsive to changes in pressure in the intake of said high-pressure pump to regulate said valve, a single valve in said by-pass conduit for regulating the amount of oil by-passed from said oil flow line into the said mixing chamber and a thermostatically controlled valve disposed in said ilow line for regulating the supply of heating medium to said heater to insure that the oil dei ers, an oil ow line connected with the supply side of the burners, a heater in said flow line, a m'uting chamber connected in said now line upstream of said heater, a low pressure pump for delivering oil fuel through said chamber to the heater, meansxfor driving said low pressure pump atconstant speed, va plurality of burner feed conduit means each connecting the oil ow line to a burner, a bypass conduit having one end connected with said oil flow line at a point adiacent to and on the downstream side of said burner eeduconduit means, the other end of said by-pass opening into said mixing chamber, a high pressure pump connected in the ilow line between the heater and the supply side of the burners for delivering the heated oil to the burners, means for driving said high pressure pump at constant speed, said mixing chamber comprising a cylindrical member, an axially disposed inlet port in the bottom thereof communicating with said low-pressure pump for supplying oil at a relatively low temperature, means maintaining the pressure at the inlet of the high-pressure pump substantially constant comprising a second by-pass conduit connecting the discharge of said low-pressure pump to the inlet of said lowpressure pump, a valve in said second by-pass conduit,

and means operatively connecting said valve tothe sucn tion end of said high-pressure pump to regulate said valve in response to a change in pressure in the suction end of said high-pressure pump, a single valvevin said bypass conduit for regulating the amount of oil by-passed from said oil flow line into the mixing chamber yand a thermostatically controlled valve disposed insaid ow line for regulating the supply of heating medium to rsaid heater to insure that the oil delivered to the burners is at a predetermined temperature. f

i References Cited in the le of this patent UNITED STATES PATENTS 'I Hobson 1 -T Sept. "l, 1959 

1. AN OIL BURNING INSTALLATION FOR A FURNACE COMPRISING A PLURALITY OF NON-SPILL TYPE PRESSURE ATOMIZING BURNERS, AN OIL FLOW LINE CONNECTED WITH THE SUPPLY SIDE OF THE BURNERS, A HEATER IN SAID FLOW LINE, A MIXING CHAMBER CONNECTED IN SAID FLOW LINE UPSTREAM OF SAID HEATER, A LOW PRESSURE PUMP FOR DELIVERING OIL FUEL THROUGH SAID CHAMBER TO THE HEATER, MEANS FOR RUNNING SAID LOW PRESSURE PUMP AT CONSTANT SPEED, A PLURALITY OF BURNER FEED CONDUIT MEANS EACH CONNECTING THE OIL FLOW LINE TO A BURNER, A BY-PASS CONDUIT HAVING ONE END CONNECTED WITH SAID OIL FLOW LINE AT A POINT ADJACENT TO AND ON THE DOWNSTREAM SIDE OF SAID BURNER FEED CONDUIT MEANS, THE OTHER END OF SAID BY-PASS OPENING INTO SAID MIXING CHAMBER, A HIGH PRESSURE PUMP CONNECTED IN THE FLOW LINE BETWEEN THE HEATER AND THE SUPPLY SIDE OF THE BURNERS FOR DELIVERING THE HEATED OIL TO THE BURNERS, MEANS FOR RUNNING SAID HIGH SPEED PUMP AT CONSTANT SPEED, SAID MIXING CHAMBER COMPRISING A CYLINDRICAL MEMBER, AN AXIALLY DISPOSED INLET PORT IN THE BOTTOM THEREOF COMMUNICATING WITH SAID LOW PRESSURE PUMP FOR SUPPLYING OIL AT A RELATIVELY LOW TEMPERATURE, MEANS MAINTAINING THE PRESSURE AT THE INLET OF THE HIGH PRESSURE PUMP SUBSTANTIALLY CONSTANT COMPRISING A SECOND BY-PASS CONDUIT CONNECTING THE DISCHARGE OF SAID LOW-PRESSURE PUMP TO THE INLET OF SAID LOW-PRESSURE PUMP, A VALVE IN SAID SECOND BY-PASS CONDUIT, AND MEANS RESPONSIVE TO CHANGES IN PRESSURE IN THE INTAKE OF SAID HIGH-PRESSURE PUMP TO REGULATE SAID VALVE, AND A SINGLE VALVE IN SAID BY-PASS CONDUIT FOR REGULATING THE AMOUNT OF OIL BY-PASSED FROM SAID FLOW LINE INTO THE SAID MIXING CHAMBER. 